1. Field of the Invention
The invention relates to a self-dumping separator with a disc stack. The self-dumping separator has a vertical axis of rotation and a drum with solids discharge openings. A disc stack made up of a plurality of conical discs is inserted into the drums. A centrifuge feed is introduced via an inlet pipe and a distributor into a centrifuge space that is enclosed by the drum. At least two or a plurality of fins is arranged in an annular solids space that is arranged radially outside the disc stack.
Self-dumping separators having disc stacks, which exhibit for example a piston slide valve or the like for the purpose of dumping, are known in the most varied embodiments. They are employed for a wide range of purposes in various types of centrifuges, for example in clarifying, separatory, or degerminating centrifuges. The preferred area of application here is the processing of dairy products and here, in particular, the degermination and separation of milk.
It is also known to provide self-dumping centrifuge drums with fins outside the disc stack. Such an arrangement is shown for example in U.S. Pat. No. 2,126,864, which shows a separator having a drum with solids discharge openings that are closable by a piston slide valve.
In self-dumping separators usual at present, cleaning problems arise under some circumstances in practice. It turns out that the cleaning effect on the drum cover and on the bottom of the centrifuge space in the drum is especially problematic and that contaminants can frequently be found there even after automatic cleaning.
2. Brief Description of the Art
Against this background, it is an object of the invention to improve the design and construction of the separator of the type stated at the outset in such fashion that an improved cleaning action can be attained.
According to the invention, the drum exhibits solids discharge openings and the clearance between the fins—or the advantageously implemented fin insert—and the inner wall of the drum at every point is at least three millimeters.
In this way the clearance between the fins and the inner shell of the drum is made so large that at every point in the solids space the clearances between the fins and the inner shell of the drum, in particular the drum cover and the bottom of the centrifuge space as well as, advantageously, at other points critical in respect of cleaning, are large enough that adequately great relative motion of the liquid relative to the drum in the circumferential direction is always permitted at the outer circumferential surface and in other marginal regions of the centrifuge space.
From U.S. Pat. No. 3,529,767 there is known a design having fins in a separator drum, individual ones of the fins (e.g., fins 51″), however, lying directly against the drum shell.
With regard to the existing art, the following are further cited: DE 567 665, DE 444,573, U.S. Pat. No. 2,662,687 and U.S. Pat. No. 2,313,541. These publications each show chamber separators having fin inserts outside the disc stack but no solids discharge openings, so that the advantages according to the invention cannot come about. U.S. Pat. No. 2,477,982 shows a self-dumping separator having discharge openings with no piston slide valve, fins outside the disc stack again extending to the drum cover. U.S. Pat. No. 5,735,789 shows a separator having a disc stack with fin-shaped spacers.